Machine for wrapping articles in heat sealable film

ABSTRACT

HEAT SEALABLE FILM IS METERED TO AN OVERWRAP MACHINE FROM TWO SUPPLY WEBS BY MECHANISM COUPLED TO THE SEALING FRAME BY WHICH THE FILM IS WRAPPED, CUT AND SEALED. THAT METERING MECHANISM PERMITS ACCURATE CENTERING OF A PATTERN PREPRINTED ON ONE OF THE SUPPLY WEBS. AN AUXILIARY &#34;TUCKER BAR&#34; IS DRIVEN IN RESPONSE TO SEALING FRAME MOVEMENT AND AIDS WRAPPING OF EACH ARTICLE PRIOR TO SEALING. A CONVENIENT AND ECONOMICAL POWER ASSIST MECHANISM IS DESCRIBED.

R. T. LAW MACHINE FOR WRAPPING ARTICLES IN Illa'Al" SEALABLE FILM Nov. 23, 197] 3 Sheets-Shoot Filed Feb. 2, 1970 if? wwwm 1110/14/15 & i wfL Lil Q &

mm m a mm w 1971 R. T. LAW 3,621,63

MACHINE FOR WRAPPING ARTICLES IN rum-r SEALABLE FILM Filed Feb. 2, 1970 3 Shects-Sheet m n lM/En/rag 77 g; 1%;: g 37 & w w li 46M,

Nov. 23, 1971 R. T. LAW

MACHINE FOR WRAPPING ARTICLES IN HEAT SEALABLE FILM 3 Sheets-Shed :5

Filed Feb. 2, i970 0 2 m m ,N I W /H J a W Wv United States Patent 3,621,633 MACHINE FOR WRAPPING ARTICLES IN HEAT SEALABLE FILM Raymond Thomas Law, Salinas, Calili, assignor to Lockwood Technical, Inc., Sand City (Seaside), Monterey County, Calif.

Filed Feb. 2, 1970, Ser. No. 7,572 Int. Cl. 1365b 11/48, 41/16, 67/08 U.S. Cl. 53-198 R 7 Claims ABSTRACT OF THE DISCLOSURE Heat sealable film is metered to an overwrap machine from two supply webs by mechanism coupled to the sealing frame by which the film is wrapped, cut and sealed. That metering mechanism permits accurate centering of a pattern preprinted on one of the supply webs. An auxiliary tucker bar is driven in response to sealing frame movement and aids wrapping of each article prior to sealing. A convenient and economical power assist mechanism is described.

This invention has to do with overwrap machines for wrapping articles of moderate size in sheet material that is sealable by heat, the sheet material being typically supplied to the machine in two strips or webs. After each wrapping operation the ends of the two webs are sealed together to form a continuous curtain in which the next article is then enveloped.

The invention is concerned more particularly with features of such machines by which they may be adapted for convenient hand operation, in the sense that objects to be wrapped are fed manually to the machine and each wrapping operation is controlled in response to manual action.

Machines of the present general type have been described, for example, in Pats. 3,016,673, issued to John M. Parker on Jan. 16, 1962, and 3,164,937, issued to Marvin L. Ingram on Jan. 12, 1965. A more complex machine has been described in Pat. 3,188,782, issued to Ezra Lapides on June 15, 1965.

One aspect of the invention provides improved metering of the sheet material or film to the wrapping site, with suitable tension and with variable rate of supply. Such variation is useful to accommodate objects of differing size and to facilitate centering of a pattern preprinted on the sheet material.

A further aspect of the invention provides a movable element which facilitates tight wrapping of each object without exerting undue tension on the film. Such an element, which will be referred to as a tucker bar, is especially, but not exclusively, useful in connection with hand feeding of the wrapping and sealing operation.

Another aspect of the invention provides a convenient and economical power assist mechanism for driving the moving parts of the machine under direct control of the operator.

A full understanding of the invention, and of its further objects and advantages, will be had from the following description of an illustrative machine embodying the invention. The particulars of that description, and of the accompanying drawings which form a part of it, are intended only as illustration and not as a limitation upon the scope of the invention, which is defined in the appended claims.

In the drawings:

FIG. 1 is a front elevation;

FIG. 2 is a side elevation;

FIG. 3 is a fragmentary section on line 3-3 of FIG. 2;

3,6ZL633 Patented Nov. 23, I971].

FIG. 4 is a schematic side elevation, representing an intermediate stage in the machine operation;

FIG. 5 is a schematic side elevation, representing a later stage in the machine operation; and

FIG. 6 is a side elevation representing a modification.

The machine frame 10 comprises the right and left side plates 12 and 14, respectively, which are rigidly joined in parallel spaced relation by the six tie rods 16. Heat sealable film is supplied to the working zone 17 of the machine via the upper and lower film webs 18 and 19 from the upper and lower supply rolls 20 and 22, respectively. Those rolls are rotatably mounted by means of the shafts 21 and 23, which are reduced in diameter at their ends to freely enter the journal slots 25. The roll centering hubs 24 are shiftable longitudinally of their respective shafts, and are locked in position, as by set screws. Film web 18 from upper supply roll 20 is led directly to the upper web control mechanism, indicated generally by the numeral 30. Film web 19 from lower roll 22 is led to the lower web control mechanism 40 via the two guide rollers 27 and 28, which are mounted for free rotation on fixed axes. Those rollers and others to be described are preferably long enough to accept a film web having a width essentially equal to the full distance between frame plates 12 and 14. However, narrower webs may be used whenever desired by moving the centering hubs 24 inward on their shafts an appropriate distance.

Unwinding of the film webs from their supply rolls is preferably limited by mild braking action of any suitable type. In the present structure the flexible brake belt 57 has one end mounted on the uppermost tie rod 16a and is draped over both supply rolls in series. The free end of the belt carries the weights 58, which provide a yieldable and conveniently variable tension. Any tendency of the belt to brake the upper supply roll more strongly due to geometry is counteracted by surfacing the belt with a material of increased coefficient of friction at the area of contact with the lower roll, as indicated at 59.

Upper web control mechanism 30 comprises the three guide rollers 32, 33 and 34, which are mounted for free rotation on horizontally spaced fixed axes as shown best in FIG. 2, and the two rollers 35 and 36, which are suspended in loops of the web between the roller pairs 32, 33 and 33, 34, respectively. Free roller 36 has its ends, which are of reduced diameter, freely guided in the vertical slots 51 in the respective frame plates 12 and 14, and acts as a tension roll. Free roller 35 acts as a dancer roll. It projects in spaced relation through the relatively wide clearance slots 52 in the frame plates, and its reduced ends are freely guided in the longitudinal slots 38 in the upper guide arm 37, to be more fully described below. Slots 38 are effectively closed at their upper ends by the adjustable stops 39, limiting the upward movement of the dancer roll.

Lower web control mechanism 40 comprises the two guide rollers 42 and 43, which are freely rotatable on horizontally spaced fixed axes, and the dancer roll 45, which is suspended in the web loop formed between rollers 42 and 43. Each end of dancer roll 45 extends in spaced relation through a clearance slot 53 in the frame plate and is freely slidable in the generally vertical slot 48 in the guide arm 47, but subject to the adjustable upper limit stop 49. Web 19 passes from lower control mechanism 40 under the further guide roller 56 and then upward to working zone 17.

Each of the control mechanisms 30 and 40 also includes lock mechanism for engaging the web at a point downstream of the dancer roll and preventing backward movement of the web, while permitting its essentially free forward movement. Such lock mechanism is shown illustratively at 31 for the upper web and at 41 for the lower web, each mechanism comprising an essentially cylindrical sleeve 54 of a suitable elastomer material mounted eccentrically on a freely rotatable shaft 55. Shaft 55 is journaled parallel to the first guide roller beyond the dancer roll and at such distance from that guide roller 33 or 43 that slight shaft rotation shifts the sleeve into and out of contact with the stationary roller, or with a film guided over it. The shafts 55 are yieldably biased in counterclockwise direction as seen in FIG. 2 toward the film engaging position, as by coil springs indicated at 55a (FIG. 1). Backward film movement then causes tight locking engagement of sleeve 54, while forward film movement is essentially unimpeded.

The wrapping and sealing mechanism at working zone 17 includes the relatively fixed horizontal sealing bar 60, which is mounted on frame plates 12 and 14 by means of the brackets 62 and the telescoping post structures 64. Those structures maintain the sealing bar normally at a definite height but resiliently permit its limited downward movement when pressed from above. Lower web 19 is guided toward sealing bar 60 over the guide roller 61, which is freely rotatable on a fixed axis. Sealing bar 60 includes electrical heating elements of conventional form, not explicitly shown, for cutting and re-sealing the film webs.

The pressure bar 70 is mounted for generally vertical movement between a working position directly overlying sealing bar 60 (FIG. 5) and an upwardly retracted idle position in parallel spaced relation to the sealing bar, as typically shown in FIG. 2. Pressure bar 70 is mounted near the forward ends of the two main side arms 76, which are pivoted at their rearward ends at 77 on the respective frame plates 12 and 14. Side arms 76 also carry the handle 80, typically comprising the stub arms 81, which are rigidly but adjustably mounted on the respective side arms, and the horizontal crossbar 82, which interconnects the ends of the stub arms. Side arms 76, handle 80 and pressure bar 70 form together an effectively rigid working frame 72, which is the primary operating member of the machine. A guide roller may be freely journaled on that frame just forward of pressure bar 70 to guide web 18 toward that bar, but such a roller is not ordinarily needed, and is omitted from the present machine. The large recesses 79 in the forward edges of side plates 12 and 14 provide clearance for the sealing bar during the limited swinging movement of working frame 72. That movement may be limited upwardly in any convenient manner, as by contact of the lower end of slot 48 in guide arm 47 with fixed pivot 89.

In addition to carrying pressure bar 70, main side arms 76 actuate the web control guide arms 37 and 47, already referred to. Each upper guide arm 37 is pivoted at its lower end on side arm 76 at 86, and its angular position about that pivot is controlled by the sliding pivot 87, which is mounted on the frame plate on a fixed axis and is slidingly received in slot 38. Similarly, each lower guide arm 47 is pivoted at its upper end on side arm 76 at 88, and its position about that pivot is controlled by the sliding pivot 89, which is mounted on the frame plate and is slidingly received in slot 48. The resulting movement of guide arms 37 and 47 in response to swinging of working frame 72 about the support pivots 77 is essentially vertical translational movement, the slight rotation about the sliding pivots 87 and 89 being negligible for practical purposes. The vertical guide arm movement has the primary function of altering the upper limit of the free travel of dancer rolls 35 and 45 by shifting the stops 39 and 49.

The swinging movement of side arms 76 also controls the motion of the tucker bar 100. That bar extends generally parallel to pressure bar 70 and has a central portion 101 that is vertically offset (FIG. 1). The ends of the tucker bar are mounted on the forward free ends of the respective support levers 102. Those levers are positioned just inward of the side plates, to which they are freely pivoted at their rearward ends at 104. The levers are yieldingly biased downwardly and are positively limited in their downward swinging movement by the main side arms 76. In the present structure, each lever 102 carries a rigid bracket 106 which extends outwardly through the clearance aperture 107 in the frame plate and carries the roller 108 in position to ride the upper surface of the side arm. The coil spring 105 extends from bracket 106 downward to a suitable mounting point, preferably on the end stop 49 on lower guide arm 54. Accordingly, as the side arms move downwardly from the position shown in FIG. 2, for example, springs 105 cause levers 102 to swing downwardly through a corresponding angle. However, since the lever arm between each roller 108 and lever pivot 104 is much shorter than the lever arm between roller 108 and side arm pivot 77, lever 102 tends to swing through a correspondingly larger angle than the side arm.

The effective weight of working frame 72 and its associated structures is preferably counterbalanced by suitable springs, so that the frame is normally held in fully raised position, as shown in FIG. 2. That normal position is preferably defined by a positive stop structure that is conveniently adjustable. As shown, the stop 109 is adjustably mounted on lower guide arm 47 and limits upward swinging of the working frame by engaging fixed pivot 89.

When springs 105 are connected as described, they not only urge tucker bar 100 downward, but also urge main working frame 72 upward. The latter effect may more than compensate the downward force exerted by rollers 108 on the side arms, due to the longer lever arm at which the lower end of each spring acts on the side arm through pivot 88. With suitable design, spring 105 may be made to fully counterbalance frame 72. Alternatively, an additional spring may be provided to supplement springs 105 in counterbalancing frame 72, or the lower ends of springs 105 may be mounted directly on the frame plates and frame 72 may be balanced by entirely separate spring means of any suitabel type.

An article 110 to be wrapped is inserted between sealing bar 60 and pressure bar onto the working surface 90, which forms effectively a rearward extension of the upper surface of the sealing bar. Surface extends rearwardly from the supporting cross beam at a downwardly inclined angle, terminating at 91 at the side wall 93 of a delivery chute 92 with laterally inclined bottom surface 94. Chute 92 opens through the rectangular aperture 96 in frame plate 12, and typically delivers wrapped and sealed articles onto a conveyor belt or the like.

In operation of the present llustrative machine, FIGS. 1 and 2 represent a typical condition of the machine after completion of one wrapping operation and ready for another. Working frame 72 has been elevated to permit insertion of another article to working zone 17. Dancer rolls 135 and 45 are spaced below their respective stops 39 and 49 by definite distances, determined in a manner to be described. The two webs 18 and 19 have been scaled together at a point indicated at 121, and extend as a vertical curtain between guide rollers 34 and 61, due to the mild tensioning action of takeup roll 36, which is at an intermediate point of its range of travel in guide slot 51.

Manual insertion of an article 110 into working zone 17 deflects curtain 120 inwardly, forming a loop which partially envelopes the article. Film is thereby drawn from one or more of the three storage loops formed by the takeup roll and the two dancer rolls 35 and 45. The tension roll is preferably appreciably lighter than the dancer rolls. Hence its loop is first exhausted, after which film is pulled from one or both of the two dancer roll loops.

If one of the webs carries a repetitive pattern which is to appear on each of the wrapped articles, the article is inserted in a manner to exhaust first the film loop at the dancer roll for that printed web, drawing that dancer roll up against its stops 39 or 49. That action may be obtained by rotating the article slightly in one direction or the other as it is inserted. Also, such selective initial consumption of film from one web or the other is preferably facilitated by making the dancer roll for the printed web lighter than that for the unprinted web. After the printed web loop has been exhausted, complete insertion of the article normally requires that some film be drawn also from the other dancer roll loop.

A typical condition of the machine after such complete insertion of an article 110 is shown in FIG. 4, assuming for illustration that lower web 19 carries the printed pattern. Lower dancer roll is raised against stops 49. Takeup roll 36 is raised to a point where its loop is substantially eliminated. Upper dancer roll 35 is raised only slightly above its position in FIG. 2, and still forms a loop of appreciable size below its stops 39. It is noted particularly that the transition from FIG. 2 to FIG. 4, brought about by insertion of article 110, ordinarily does not draw any film from either of the supply rolls 20 and 22 against the frictional resistance of brake 57.

The next step of the wrapping process is performed by lowering working frame 72 by downward pressure on handle bar 82. As side arms 76 swing downward about their fixed pivots 77, rollers 108 are lowered, permitting springs 105 to swing the tucker bar support levers 102 downward ahead of working frame 72. Tucker bar 100 thereby engages the upper run of film between pressure bar and the inserted article, deflecting that run downward to closely wrap the forward face of the article. That wrapping action by the tucker bar firmly encloses the article in film, and is particularly helpful in wrapping leafy articles such as celery heads, for example. The tucker bar further anchors the article positively in proper position, so that it can be released by the operator as the sealing bar comes down. The vertical offset 101 at the center of the tucker bar (FIG. 1) provides clearance for the operator to retain control of the article until the tucker bar has descended. As tucker bar comes to rest on the forward portion of working surface 90, further downward movement of working frame 72 causes rollers 108 to lift from side arm 76. At the lower end of the working frame travel, shown typically in FIG. 5, pressure bar 70 presses the two runs of film flatly together and against the upper surface of sealing bar 60, which then operates in conventional manner to cut both runs of the film and to seal together the two runs on both sides of the cut. That dual sealing action seals the wrapping around the article and also seals together the remaining ends of webs 18 and 19, as indicated in FIG. 2 at 121.

During the downward movement of working frame 72 the two sets of dancer roll stops 39 and 49 are moved positively downward, forcing their respective dancer rolls down and enlarging those web loops. Since the locking mechanisms 31 and 41 prevent backward movement of film toward those loops, the entire increase in loop size is accomplished by drawing fresh film from supply rolls 20 and 22. Since the dancer roll for the printed web was initially against its stops (shown in FIG. 4 for roll 45), its downward travel corresponds directly to the full travel of working frame 72, insuring that a uniform length of film is drawn from the supply roll during each wrapping operation. That film length can therefore be made accurately equal to the pattern interval by suitable adjustment of the dancer roll stops 49 and of limit stops 109 for the upward frame movement. Any irregularity in the amount of film required for wrapping successive articles appears entirely as variation in the length of film drawn from the unprinted supply roll. An experienced operator can readily vary the depth of insertion of each article to obtain tight wrapping regardless of size variations.

After the described cutting and sealing operation has been completed, working frame 72 is returned to its idle raised position (FIG. 2). During that movement, stops 39 and 49 are lifted from their respective dancer rolls, typically leaving those rolls and their formed film loops unchanged. The small loop of film at the fresh seal 121 is drawn taut by downward movement of takeup roll 36, reestablishing the vertical film curtain across working zone 17, ready for insertion of the next article.

FIG. 6 represents a preferred manner of modifying the structure previously described to provide power assisted drive of working frame 72 in its swinging movement about pivots 77. The two-way air cylinder is pivotally supported at one end at 132 on frame plate 12. The piston rod 134 of that cylinder is pivotally connected at 135 effectively to side arm 76, but actually to the projecting upper end of guide arm 47. The four-way control valve is mounted rigidly on side arm 76 at a suitable spacing back of its forward end, with the valve operating lever at 142. The stub arm 81a of the handle assembly is mounted at 143 at the forward end of side arm 76 for free pivotal movement, with the torsion spring 144 acting between the side arm and stub arm to maintain a normal angular relation such as that shown in the figure. Cam surfaces 146 are formed on the rearwardly projecting end of stub arm 81a in position to operate valve arm 142 in one direction from its neutral position in response to downward swinging of the handle and in the other direction in response to upward handle movement.

The air supply and delivery system includes the flexible supply tube 150, which connects to the nipple 151, typically mounted on frame plate 12 by the bracket 152; the tube 153 between nipple 151 and the inlet of valve 140; the down-drive tube 154, which connects one valve outlet to the upper end of cylinder 130; and the up-drive tube 158, which connects the other valve outlet to the lower end of cylinder 130. The latter two tubes include in series the T-fittings 155 and 159, respectively, which supply driving air to the respective ends of a similar air cylinder mounted on the other frame plate .14 and driving the side arm 76 on the other side of the machine. Connections between the two sides of the machine are conveniently made through rigid tubes which serve also as tie rods 16 of the frame structure.

Control valve 140 is typically of the conventional type in which air is cut off from both outlets in equilibrium position of control lever 142, and is delivered at progressively increasing rate to one or other outlet in response to increasing movement of the control lever in respective directions, the other outlet being connected to the atmosphere. The rate of movement of the working frame in either direction is then directly controllable by the angular departure of handle 80 from its equilibrium relation to side arms 76, which departure, in turn, is proportional to the force applied to the handle in either direction. After contact has been established between the sealing bar and pressure bar, the pressure exerted on the film during the sealing and cutting process depends essentially on the air pressure supplied to supply line 150. That pressure may be conveniently adjusted by use of a conventional pressure reduction valve in the supply line.

The machines that have been described are capable of sleeve wrapping a wide variety of articles. For many purposes such film wrapping can be made sufficiently tight to require no further processing. However, if desired, the wrapped article may be passed through a conventional shrink tunnel to close the sleeve ends and further tighten the wrapping.

What is claimed is:

1. An overwrap machine, comprising in combination a machine frame,

a generally horizontal sealing bar mounted on the frame, with a working surface extending rearwardly therefrom for supporting an article to be wrapped,

a pressure bar mounted for movement along a generally vertical path between an idle position spaced above the sealing bar and an active position directly overlying the sealing bar for performing therewith a sealing operation on heat sealable film between the bars,

film supply means for providing a curtain of heat sealable film extending generally vertically forward of the bars and yieldable rearwardly to permit insertion between the bars of an article to be Wrapped,

a tucker bar mounted for movement along a path generally parallel to, and rearward of, said pressure bar path between an idle position spaced above the working surface and an active position adjacent the working surface,

means for driving the pressure bar downwardly along its path and for returning it to idle position after a sealing operation,

and means for driving the tucker bar downwardly along its path in advance of the downward movement of the pressure bar, and for returning the tucker bar to idle position,

said tucker bar including an upwardly offset portion intermediate its ends, said offset portion being spaced from said working surface in said active position of the tucker bar and forming an aperture through which an operator can manipulate an inserted article despite downward movement of the tucker bar.

2.- An overwrap machine as defined in claim 1, and in which said working surface is inclined rearwardly downward from the sealing bar within the machine frame at an angle sufficient to cause a wrapped and sealed article to move rearwardly along it,

said machine including a laterally inclined delivery chute for receiving wrapped and sealed articles from the rearward end of the working surface and for delivering such articles laterally to the exterior of the machine frame.

3. An overwrap machine, comprising in combination a machine frame,

a generally horizontal sealing bar mounted on the frame, with a working surface extending rearwardly therefrom for supporting an article to be wrapped,

a pressure bar mounted for movement along a generally vertical path between an idle position spaced above the sealing bar and an active position directly overlying the sealing 'bar for performing therewith a sealing operation on heat sealable film between the bars, said pressure bar being carried on a working frame which is mounted on said machine for swinging movement about a first pivot axis parallel to the pressure bar and spaced rearwardly thereof,

film supply means for providing a curtain of heat sealable film extending generally vertically forward of the bars and yieldable rearwardly to permit insertion between the bars of an article to be wrapped,

a tucker bar mounted for movement along a path generally parallel to, and rearward of, said pressure bar path between an idle position spaced above the working surface and an active position adjacent the working surface, said tucker bar being carried on a tucker bar frame which is mounted on the machine frame for swinging movement about a second pivot axis parallel to the pressure bar and spaced rearwardly thereof,

means for driving the pressure bar downwardly along its path, and for returning it to idle position after a sealing operation,

and means including coupling mechanism acting between the working frame and the tucker bar frame for driving the tucker bar downwardly along its path in advance of the downward movement of the pressure bar, and for returning the tucker bar to idle position.

4. An overwrap machine as defined in claim 3, and in which said means for driving the tucker bar includes spring means urging downward movement of the tucker bar frame, and said coupling mechanism comprises first and second formations on the tucker bar frame and on the working frame, respectively, interengageable to limit downward movement of the first formation relative to the second formation.

5. An overwrap machine as defined in claim 3, and

including also a handle mounted on the working frame remotely from said first pivot axis for vertical movement relative to the working frame through a limited range of movement,

spring means urging the handle toward a neutral position within its said range of movement,

a fluid actuated motor coupled between the working frame and the machine frame for driving said swinging movement of the working frame up and down in response to pressurized fluid supplied selectively to respective up and down inlet lines,

a source of pressurized fluid,

valve mechanism mounted on the working frame and receiving pressurized fluid from the source,

and control mechanism coupled between the handle and the valve mechanism for causing the valve mechanism to supply pressurized fluid selectively to the up and down inlets of the motor in response to relative handle movement upwardly and downwardly, respectively, from said neutral position with respect to the working frame.

6. An overwrap machine as defined in claim 3, and in which said film supply means include a supply roll of heat sealable film rotatably mounted on the frame,

guide means for leading the film from the roll forwardly to one edge of the curtain and including roller structure forming a film loop,

a dancer roll in the loop, F

structure guiding the dancer roll for free rotational movement and for translational movement to vary the size of the loop,

film engaging ratchet structure for preventing film movement backward toward the loop,

link structures coupled to the working frame at opposite sides thereof between the first pivot axis and the pressure bar,

and adjustable coupling mechanism between the link structures and the respective ends of the dancer roll for driving the dancer roll in its translational movement in response to said swinging movement of the working frame to expand the loop and thereby to draw a metered length of film from the supply roll during each cycle of movement of the pressure bar.

7. An overwrap machine, comprising in combination a machine frame,

an elongated sealing bar mounted on the frame,

a working frame mounted on the machine frame for relative swinging movement about a pivot axis parallel to the sealing bar and carrying a pressure bar in position to be spaced from the sealing bar in idle position of the working frame and to cooperate with the sealing bar for sealing heat sealable film therebetween in active position of the working frame,

film supply means for providing a curtain of heat sealable film extending between the bars on one side thereof in idle position of the Working frame, said curtain being yieldable to permit insertion of an article to be Wrapped between the bars from said one side,

a handle mounted on the working frame remotely from the pivot axis and movable relative to the working frame circumferentially with respect to the pivot axis through a limited range of movement,

1Q spring means urging the handle toward a neutral posiin the respective directions of working frame movetion within its range of movement, ment. a fluid actuated reversible motor having drive and re- References Cited turn inlets and coupled betvveen the Working frame UNITED STATES PATENTS and the machine frame, sard motor actmg to drive 5 the working frame about said axis to active position 2,860,466 11/1958 Ingram 53' 389 X and to return the Working frame to idle position in 3,078,632 2/1963 Fmman 53*373 X response to supply of pressurized fluid selectively to 31091462 7/1963 Langdon 53 373 X the respective drive and return inlets, 11953289 7/1965 Cochran: 53*390' X a source of pressurized fluid 10 3,420,034 1/1969 szualsky et al. 53-182 valve mechanism mounted on the Working frame and 34691368 9/1969 Churchln at 53 229 receiving pressurized fluid from the source, and control mechanism coupled between the handle THERON CONDON Pnmary Examma'r and the valve mechanism for causing the valve N. ABRAMS, Assistant Examiner mechanism to supply pressurized fluid selectively to 15 U 8 C1 X R the drive and return inlets of the motor in response to relative handle movement from neutral position 53389 390 

